The present invention relates to an integrated services hub (ISH) for use with broadband packet networks, and more specifically it relates to a method and apparatus for polling the status of telephony lines connected to the ISH in order to minimize power consumption when the ISH is operating on battery backup power.
Traditionally, telephony communications within the United States were handled by the public switched telecommunications network (PSTN). The PSTN can be characterized as a network designed for voice communications, primarily on a circuit-switched basis, with full interconnection among individual networks. The PSTN network is largely analog at the local loop level, digital at the backbone level, and generally provisioned on a wireline, rather than a wireless, basis. The PSTN includes switches that route communications between end users. Circuit switches are the devices that establish connectivity between circuits through an internal switching matrix. Circuit switches set connections between circuits through the establishment of a talk path or transmission path. The connection and the associated bandwidth are provided temporarily, continuously, and exclusively for the duration of the session, or call. While developed to support voice communications, circuit switches can support any form of information transfer (e.g., data and video communications).
In a traditional PSTN environment, circuit switches include central office (CO) exchanges, tandem exchanges, access tandem exchanges, and international gateway facilities. Central offices, also known as exchanges, provide local access services to end users via local loop connections within a relatively small area of geography known as an exchange area. In other words, the CO provides the ability for a subscriber within that neighborhood to connect to another subscriber within that neighborhood. Central offices, also known as end offices, reside at the terminal ends of the network. In other words, COs are the first point of entry into the PSTN and the last point of exit. They are also known as class 5 offices, the lowest class in the switching hierarchy. A class 5 telephone switch communicates with an analog telephone using the analog telephony signals in the well-known analog format. The class 5 telephone switch provides power to the telephone; detects off-hook status of the telephone and provides a dial tone in response; detects dual-tone multi-frequency signals from the caller and initiates a call in the network; plays a ringback tone to the caller when the far-end telephone is ringing; plays a busy tone to the caller when the far-end telephone is busy; provides ring current to the telephone on incoming calls; and provides traditional telephone services such as call waiting, call forwarding, caller ID, etc.
In an effort to increase the amount and speed of information transmitted across networks, the telecommunications industry is shifting toward broadband packet networks which are designed to carry a variety of services such as voice, data, and video. For example, asynchronous transfer mode (ATM) networks have been developed to provide broadband transport switching capability between local area networks (LANs) and wide area networks (WANs). The Sprint ION network is a broadband network that is capable of delivering a variety of services such as voice, data, and video to an end user at a residential or business location. The Sprint ION network has a wide area IP/ATM or ATM backbone that is connected to a plurality of local loops via multiplexors. Each local loop carries ATM over ADSL (asymmetric digital subscriber line) traffic to a plurality of integrated service hubs (ISHs), which may be at either residential or business locations.
An ISH is a hardware component that links business or residential user devices such as telephones and computers to the broadband, wide area network through a plurality of user interfaces and at least one network interface. A suitable ISH is described in co-pending U.S. patent application Ser. No. 09/226,575 entitled xe2x80x9cMulti-Services Communications Device,xe2x80x9d filed on Jan. 7, 1999 (Sprint docket number 1246), which is incorporated by reference herein in its entirety. The network interface typically is a broadband network interface such as ADSL, T1, or HDSL-2. Examples of user interfaces include telephone interfaces such as plain old telephone system (POTS) ports for connecting telephones, fax machines, modems, and the like to the ISH; computer interfaces such as ethernet ports for connecting computers and local area networks to the ISH; and video ports such as RCA jacks for connecting video players, recorders, monitors, and the like to the ISH.
In providing telephony services over a broadband network, the ISH connects a telephone in the customer""s premises to a network element such as a service manager. This connection between the telephone and the network element is typically an ATM connection, which is much different than the traditional analog line to the local switch. ATM connections usually do not support analog telephony signals, such as off-hook, dial tone, and busy signals. Therefore, the ISH must provide many of the telephony functions traditionally provided by the telephone provider central office such as detect off-hook conditions, on-hook connections, and digits as well as provide the telephones with dial tone, ring current, ringback, and busy signals. The terms off-hook and off-hook condition as used herein are generic terms meaning that a user device (whether telephone, facsimile machine, modem, etc.) connected to a telephone line is attempting to access and use the line.
Another example of such a central office function being provided by the ISH is backup power. Traditionally in cases of power grid failure, the central office provides backup power to customers"" telephones through use of an industrial-strength, petroleum-fueled backup generator. Since it is not economical to equip each customer with a backup generator, an ISH must be equipped with an back-up power supply, which is typically a battery pack, to maintain power to the system in cases of power grid failure. The use of telephony services impacts how long the batteries can keep the ISH operational because more power is required to maintain phone lines in active (i.e., conversational) state as opposed to standby (i.e., on-hook) or disabled states. Likewise, the number of telephone interfaces impacts battery life, as the amount of power used by the ISH increases with the number of telephone interfaces being served. The present invention addresses the need to preserve battery power by maintaining the supported telephone interfaces in a disabled state and only periodically and sequentially powering-up the supported telephone interfaces to a standby state to check whether there is a need to enable full power and service (i.e., active state) to a given interface.
The present invention discloses a method for reducing battery power consumed by an integrated services hub supporting a plurality of telephone lines, comprising monitoring the status of power to the integrated services hub; upon detecting a failure of primary power, polling each of the telephone lines to detect an off-hook condition; monitoring the status of power to the integrated services hub while polling; and stopping polling upon detecting a return of primary power to the integrated services hub or upon detecting an off-hook condition in one of the telephone lines. The step of polling each of the telephone lines to detect an off-hook condition further comprises placing one of the telephone lines in a standby state and the remaining telephone lines in a disabled state, monitoring the telephone line in standby state for a predetermined amount of time to detect an off-hook condition; after the predetermined amount of time has lapsed, changing the monitored telephone line from standby state to disabled state, placing the next of the plurality of telephone lines in a standby state, and maintaining any remaining telephone lines in a disabled state; and repeating this sequence.
The present invention further discloses an apparatus for reducing battery power consumed by an integrated services hub supporting a plurality of telephone lines, comprising at least one subscriber line interface circuit (SLIC), the SLIC having the ability to be placed in a disabled state, a standby state, and an active state and each of the telephone lines being connected to a SLIC; at least one component to detect an off-hook condition in the telephone lines connected to the SLIC; a power monitor for monitoring the status of power to the integrated services hub; and a polling controller, the polling controller receiving notification from the power monitor regarding the status of power to the integrated services hub, the polling controller receiving notification from the component to detect an off-hook condition regarding the condition of the telephone lines, and the polling controller altering the state of the SLIC in response to the notifications from the power monitor and the component to detect an off-hook condition. Preferably, the component to detect an off-hook condition in the telephone lines is a subscriber line access circuit (SLAC).